Meta Post - Common CSS Hacks

[wonton]

@Klaas Try adding this code and see if it works?

.outline .collapsible-item-children {
  margin-left: 20px;
  border-left: 1px solid rgba(118,158,165,0.2);
  border-radius: 4px;
  transition:all 0.5s ease-in-out;
}
.outline .collapsible-item-children:hover {
  border-left-color: rgba(118,158,165,0.4);
}